Method to optimize pipe load limits on a turbine casing

Abstract

A method is described for establishing load limits for pipe connections to a turbine casing including the steps of: identifying a plurality of the pipe connections as key pipe load connections; developing transfer functions to model deformation of the casing based on loads applied to the key pipe connections; establishing individual load limits for each of the key pipe connections in the group by optimizing solutions to the transfer functions, and establishing a cumulative load limit for the group of key pipe load connections by optimizing solutions to the transfer functions.

1. A method for establishing load limits for pipe connections to a turbine casing comprising:
 a. identifying a plurality of the pipe connections as key pipe load connections on the turbine casing, wherein the key pipe load connections is a subset of all pipe load connections on the turbine casing; 
 b. developing transfer functions to model deformation of the turbine casing based on loads applied to the key pipe connections; 
 c. establishing individual load limits for each of the key pipe connections by optimizing solutions to the transfer functions, and 
 d. establishing a cumulative load limit for the key pipe load connections by optimizing solutions to the transfer functions. 
 
   
   
     2. A method for establishing load limits as in  claim 1  wherein steps (a) to (d) are performed using a Design of Experiments process. 
   
   
     3. A method for establishing load limits as in  claim 1  wherein the key pipe connections are selected using a Screening Design of Experiments process. 
   
   
     4. A method for establishing load limits as in  claim 1  wherein the key pipe connections are a subset of a group of pipe connections. 
   
   
     5. A method for establishing load limits as in  claim 1  wherein the individual load limits are determined based on an assumption that other key pipe connections are at a maximum value. 
   
   
     6. A method for establishing load limits as in  claim 1  wherein the transfer functions are developed based on a finite element analysis of a mesh model of the casing and vectored pipe loads applied to the mesh model. 
   
   
     7. A method for establishing load limits for pipe connections to a turbine casing comprising:
 a. modeling the turbine casing as a finite element mesh model of the casing and modeling pipe loads as force vectors applied to the mesh model; 
 b. identifying key pipe connections from the pipe connections which primarily cause turbine casing deformation by analyzing the pipe loads applied to the mesh model, wherein the key pipe connections is a subset of all pipe connections on the turbine casing; 
 c. developing a transfer function representing a deflection of the turbine casing in response to pipe loads applied at each of the key pipe connections; 
 d. determining a maximum acceptable deflection of the turbine casing; 
 e. establishing a pipe load limit for each of the key pipe loads based on the transfer function and the maximum acceptable deflection, and 
 f. establishing a pipe load limit for a plurality of the key pipe loads based on the transfer function and the maximum acceptable deflection. 
 
   
   
     8. A method for establishing load limits as in  claim 7  wherein steps (b) to (f) are performed using a Design of Experiments process. 
   
   
     9. A method for establishing load limits as in  claim 7  wherein the key pipe connections are selected using a Screening Design of Experiments process. 
   
   
     10. A method for establishing load limits as in  claim 7  wherein the key pipe connections are selected from a group of pipe connections, and the key pipe load connections has fewer pipe connections than the group of pipe connections. 
   
   
     11. A method for establishing load limits as in  claim 7  wherein the individual load limits are determined based on an assumption that other key pipe connections are at a maximum value.